This invention relates to gas meters of the general type shown in U.S. Pat. No. 2,554,665 dated Mar. 13, 1951, and is particularly directed to means to prevent tampering with the meter by unauthorized persons to produce an erroneous indication of the amount of gas having been consumed. Because of the dramatic increase in the cost of gas and other energy in recent years, the amount of tampering with gas meters by the consumers in an effort to alter or prevent registration of gas flowing throught the meter has also risen dramatically. Gas utilities and manufacturers of gas meters have, therefore, become increasingly concerned with the development of means to prevent such tampering.
The usual methods employed to prevent or alter meter registration are to either alter the flow through the meter by completely bypassing the meter or reversing the flow through the meter, either of which required disconnection of the meter from the pipeline, or gaining access to the interior of the meter to cause the mechanism within the meter to produce an erroneous indication of the gas passed through the meter.
The prior art discloses numerous attempts to prevent tampering with gas meters, typical of which are the U.S. patents to Perkes U.S. Pat. No. 101,501; Moody U.S. Pat. No. 616,128; Walker U.S. Pat. No. 1,473,751; Sauton U.S. Pat. No. 1,579,954; Rockenbauer U.S. Pat. No. 1,678,955; Rutten U.S. Pat. No. 1,814,412; Morreale et al U.S. Pat. No. 1,919,701; and Talaga U.S. Pat. No. 2,067,028. In each case, however, the devices disclosed in the prior art are excessively complicated, expensive to manufacture, require special connections to connect the meter to the pipeline, or are simply inadequate to provide the necessary degree of security. The patent to Perkes for example shows a two-part device which prevents disconnect of two pipes so long as the two parts of the device are held together by a screw, access to which is guarded by seal material. Not only is this device complicated, but requires a seal which can be removed and then replaced at the will of the consumer.
The patent to Moody shows a cap 7 which prevents rotation of the connecting nut 3 so long as the seal material 10 is in place. Such an arrangement not only requires a special pipe having slots 5, but is also dependent on the presence of seal material 10 which can be removed and then replaced.
The patent to Walker shows a water meter in which the removal of an access plate is prevented by a bar which spans the access plate, the bar being locked to the coupling nuts by means of which the meter is mounted in the pipeline. Unauthorized disengagement of the nuts is prevented by sealed wire which is threaded through registering openings in the nuts. Again, the disclosed arrangement requires a seal as well as coupling nuts of special design to accomodate the seal wire and the sealing bar. Additionally, a lock is required to prevent removal of the sealing bar.
The patent to Sauton shows an elaborate, complicated arrangement in which a bar comprised of members 5 and mating members 10 and 11 extend across the top of the meter from a housing arrangement which encloses the nuts connecting the external pipeline to the inlet and outlet of the meter. Not only is the protective arrangement complicated and exensive, but as stated on page 3, lines 68-80 it may be removed with relatively little effort by a knowledgable person.
The patent to Rockenbauer discloses a two-part enclosure for enclosing the swivel nut which connects the inlet and outlet pipes to the pipeline. The two parts are connected together by "clinching" metallic tabs from one part over a portion of the other part to thereby hold it together. According to the teachings of this patent, any attempt to bend the tongues or lugs to effect a disconnect between the two portions will cause the tongues to break off thereby making attempts at tampering apparent. However, in conventional production methods, it is difficult to control the composition of the material and the strength of the tabs so that they will not break off when they are first bent in initial assembly, but will break off the first time any future attempt is made to bend them. Often times such tabs will break off during initial assembly or with care may subsequently be bent to allow disassociation of the two parts.
The patent to Rutten also shows a two-part enclosure enclosing the swivel nuts which connect the inlet and outlet of the gas meter into the exterior piping. However, this device also requires the use of a seal which unless carefully applied, can be manipulated to allow access to the interior of the enclosure or may be carefully removed and replaced after access has been gained to the swivel nut.
The patent to Morreale et al discloses two-part caps enclosing the swivel nuts with a bar integrally formed on and extending between the caps enclosing the swivel nuts at the inlet and outlet of the meter. The two parts of the cap embrace the swivel nut and are locked together by a conventional lock. Again, the disclosed arrangement requires a separate lock, which is relatively expensive and is subject to being "picked."
The patent to Talaga shows an enclosure enclosing a swivel nut which is comprised of a cap 16 and a destructible washer member 24. A one-way drive connection between the hexagonal cap 16 and internally threaded sleeve 20 is provided by means of roller pin 23 and slot 22. The pipe 11 is connected to pipe 12 by rotating the cap member 16 in the proper direction to thread the sleeve 20 onto the threaded portion 21 of the pipe 12. The one-way drive connection establishes a drive connection to drive the sleeve 20 in a direction to tighten the connection, but will allow the cap 16 to rotate freely relative to the sleeve 20 when rotated in a direction to disconnect the two pipes. In order to remove the cap 22 and gain access to the interior thereof, it is necessary to destroy the washer member 24, In this case it should be noted that the cap or shell 16 which encloses the sleeve 20 is also part of the means to achieve a connection between the pipes 11 and 12. Thus, this device represents a specialized pipe connection which cannot be applied to conventional swivel nuts and cannot be applied to meters already in the field which employ conventional swivel nuts.
It is therefore an object of applicant's invention to provide means to prevent undetectable disconnection of the meter from the line and/or access to the interior of the meter which means is simple, economical to manufacture, does not require a special arrangement to connect the meter to the external piping, can be applied to swivel nuts employed on meters already in the field, and does not require the use of the sealing devices to prevent unauthorized access to the swivel nut connecton. To achieve this applicant has provided a two-part enclosure cap which loosely encloses a conventional swivel nut and is comprised of two cylindrical sleeve members, one telescoped within the other, with means to prevent disassembly of the two members once they are assembled together to enclose the swivel nut, whereby access to the swivel nut cannot be gained without destroying one or both members.
In another form of the invention a closure plate extending between the inlet and outlet of the meter closes an access opening in the top of the meter, unauthorized removal of the plate being prevented by the two-part swivel nut enclosure.